Mask



FIG. 1 is an isometric view of a mask showing my new design.

FIG. 2 is a front elevation view thereof.

FIG. 3 is a top plan view thereof.

FIG. 4 is a left side elevation view thereof.

FIG. 5 is a right side elevation view thereof.

FIG. 6 is a rear elevation view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown represent unclaimed subject matter and form no part of the claimed design. 

The ornamental design for a mask, as shown and described. 